// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/gl/test/gl_test_helper.h"

#include <string>

#include "base/memory/scoped_ptr.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace gl {
// static
GLuint GLTestHelper::CreateTexture(GLenum target)
{
    // Create the texture object.
    GLuint texture = 0;
    glGenTextures(1, &texture);
    glBindTexture(target, texture);
    glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    return texture;
}

// static
GLuint GLTestHelper::SetupFramebuffer(int width, int height)
{
    GLuint color_buffer_texture = CreateTexture(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, color_buffer_texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA,
        GL_UNSIGNED_BYTE, nullptr);
    GLuint framebuffer = 0;
    glGenFramebuffersEXT(1, &framebuffer);
    glBindFramebufferEXT(GL_FRAMEBUFFER, framebuffer);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
        color_buffer_texture, 0);
    if (glCheckFramebufferStatusEXT(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
        EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
            glCheckFramebufferStatusEXT(GL_FRAMEBUFFER))
            << "Error setting up framebuffer";
        glDeleteFramebuffersEXT(1, &framebuffer);
        framebuffer = 0;
    }
    glBindFramebufferEXT(GL_FRAMEBUFFER, 0);
    glDeleteTextures(1, &color_buffer_texture);
    return framebuffer;
}

// static
bool GLTestHelper::CheckPixels(int x,
    int y,
    int width,
    int height,
    const uint8_t expected_color[4])
{
    int size = width * height * 4;
    scoped_ptr<uint8_t[]> pixels(new uint8_t[size]);
    const uint8_t kCheckClearValue = 123u;
    memset(pixels.get(), kCheckClearValue, size);
    glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels.get());
    int bad_count = 0;
    for (int yy = 0; yy < height; ++yy) {
        for (int xx = 0; xx < width; ++xx) {
            int offset = yy * width * 4 + xx * 4;
            for (int jj = 0; jj < 4; ++jj) {
                uint8_t actual = pixels[offset + jj];
                uint8_t expected = expected_color[jj];
                EXPECT_EQ(expected, actual) << " at " << (xx + x) << ", " << (yy + y)
                                            << " channel " << jj;
                bad_count += actual != expected;
                // Exit early just so we don't spam the log but we print enough to
                // hopefully make it easy to diagnose the issue.
                if (bad_count > 16)
                    return false;
            }
        }
    }

    return !bad_count;
}

} // namespace gl
